The Effect of Sedimentary Texture on Beach Fill Longevity
Keywords:Coastal protection, beach nourishment, beach, shoreface, barrier island, sediment distribution, heavy minerals, North Sea
Artificial beach nourishment is commonly used to protect coasts. Several publications have emphasized the influence of grain-size on beach fill design. Most of the works are based on theoretical considerations, but the models are rarely tested in the field. Three beach nourishment projects on the islands of Norderney and Langeoog were investigated in detail to obtain more information on the effects of sedimentary textures, such as grain-size and density, on beach fill longevity. Norderney is characterized by a number of solid coastal protection structures. In contrast, Langeoog has neither groynes nor revetments; the island is protected only by dunes. Additionally, artificial beach nourishment is necessary from time to time to compensate for the lack of natural sediment supply. The investigations on both islands and experiments on the hydrodynamic behaviour of sediment particles in the laboratory demonstrate that grain-size has only a small effect on beach fill longevity; however longevity is strongly influenced by grain density.